error for already purchased claims

lbry/error/README.md

@@ -59,6 +59,7 @@ Code | Name | Message
 421 | InvalidPassword | Password is invalid.
 422 | IncompatibleWalletServer | '{server}:{port}' has an incompatibly old version.
 423 | TooManyClaimSearchParameters | {key} cant have more than {limit} items.
+424 | AlreadyPurchased | You already have a purchase for claim_id '{claim_id}'. Use --allow-duplicate-purchase flag to override.
 431 | ServerPaymentInvalidAddress | Invalid address from wallet server: '{address}' - skipping payment round.
 432 | ServerPaymentWalletLocked | Cannot spend funds with locked wallet, skipping payment round.
 433 | ServerPaymentFeeAboveMaxAllowed | Daily server fee of {daily_fee} exceeds maximum configured of {max_fee} LBC.

lbry/error/__init__.py

@@ -258,6 +258,16 @@ class TooManyClaimSearchParametersError(WalletError):
         super().__init__(f"{key} cant have more than {limit} items.")
 
 
+class AlreadyPurchasedError(WalletError):
+    """
+    allow-duplicate-purchase flag to override.
+    """
+
+    def __init__(self, claim_id):
+        self.claim_id = claim_id
+        super().__init__(f"You already have a purchase for claim_id '{claim_id}'. Use")
+
+
 class ServerPaymentInvalidAddressError(WalletError):
 
     def __init__(self, address):

lbry/extras/daemon/daemon.py

@@ -38,7 +38,7 @@ from lbry.dht.peer import make_kademlia_peer
 from lbry.error import (
     DownloadSDTimeoutError, ComponentsNotStartedError, ComponentStartConditionNotMetError,
     CommandDoesNotExistError, BaseError, WalletNotFoundError, WalletAlreadyLoadedError, WalletAlreadyExistsError,
-    ConflictingInputValueError
+    ConflictingInputValueError, AlreadyPurchasedError
 )
 from lbry.extras import system_info
 from lbry.extras.daemon import analytics
@@ -2295,11 +2295,7 @@ class Daemon(metaclass=JSONRPCServerType):
             # TODO: use error from lbry.error
             raise Exception("Missing argument claim_id or url.")
         if not allow_duplicate_purchase and txo.purchase_receipt:
-            # TODO: use error from lbry.error
-            raise Exception(
-                f"You already have a purchase for claim_id '{claim_id}'. "
-                f"Use --allow-duplicate-purchase flag to override."
-            )
+            raise AlreadyPurchasedError(claim_id)
         claim = txo.claim
         if not claim.is_stream or not claim.stream.has_fee:
             # TODO: use error from lbry.error